Conventionally, various types of vehicle seat slide devices have been proposed. For example, a vehicle seat device disclosed in Patent Document 1 includes a pair of lower rails fixed on a vehicle floor and a pair of upper rails fixed to a seat. The upper rails are supported by the lower rail to be movable relative to the lower rails. Each lower rail has a pair of plate-like stoppers at a center portion in the longitudinal direction. The stoppers are formed by cutting and raising parts of the bottom wall portion of the lower rail. On the other hand, each upper rail has a pair of plate-like stoppers at either end in the longitudinal direction. The stoppers are formed by cutting and raising parts of the vertical wall portions of the upper rail. The stoppers at each end of the upper rails can contact and be engaged with the stoppers of the lower rails along the moving direction of the upper rails, so that the range of movement (slide stroke) of the upper rails relative to the lower rails is limited.
In contrast, in a vehicle seat slide device disclosed in Patent Document 2, an L-shaped stopper bracket is fixed to an upper rail, while a pin is fixed to a lower rail by swaging. The movement range of the upper rail relative to the lower rail is limited by causing the stopper bracket to contact the pin.
According to the vehicle seat slide device of Patent Document 1, even if the dimensions of the rails are the same, the positions of the stoppers, which are cut and raised from the lower rails and the upper rails, need to be changed in order to change the movement range of the upper rails relative to the lower rails. Thus, the rails need to be manufactured as specialized parts that have been subjected to a process (cutting) in accordance with a desired movement range. In other words, as lower rails and upper rails, multiple types of parts, which have been subjected to different processes in accordance with various movement ranges, need to be prepared.
On the other hand, according to the vehicle seat slide device of Patent Document 2, a separately formed stopper bracket is attached to and fixed to an upper rail. Thus, the movement range of the upper rail relative to the lower rail is easily changed. However, since the stopper bracket needs to be attached from the inside of the upper rail, which has a substantially U-shaped cross section, the installment of the stopper bracket is troublesome.    Patent Document 1: Japanese Laid-Open Patent Publication No. 2006-298104    Patent Document 2: Japanese Laid-Open Patent Publication No. 2006-15804